The only Latin I know is mea culpa,

I'm about the same, although one Latin phrase that really stuck was the motto of the Order of St. John: "pro fide, pro utilitate hominem", which we cadets were taught as "for the faith, for the service of mankind." What always struck me as ironic is that one of my corp's chief instructors was devoutly, passionately, atheist in philosophy. I wish I had asked which "fide" she was serving.